It has been previously proposed to provide key-actuated safety mechanisms for rifles and shotguns, as shown in U.S. Pat. No. 3,553,877 of Welch et al., issued Jan. 12, 1971, and U.S. Pat. No. 4,261,127 of Karkkainen, issued Apr. 14, 1981. However, such safety mechanisms are too complicated and bulky for use in the hand grips of handguns.
It has also been previously proposed to provide key-actuated locks for safety mechanisms in handguns, as shown in U.S. Pat. No. 2,945,316 of Mulno, issued Jul. 19, 1960, and U.S. Pat. No. 4,136,475 of Centille, issued Jan. 4, 1979. However, in both of these prior apparatus, a worm gear or a rack-and-pinion gear is operated by the key-actuated lock for operation of the safety mechanism, which is complicated and expensive. Also, such gear type safety mechanisms are operated by a lock extending through the bottom end of the hand grip, which takes up too much room. In the case of the Mulno patent, his worm gear safety mechanism may be also employed for shotgun or semi-automatic rifle extending through the side of the main frame.
A combination lock has been proposed for operating a safety mechanism in a handgun, as shown in U.S. Pat. No. 774,712 of Vold, issued Nov. 8, 1904. However, this does not have the simplicity and convenience of a key-actuated lock and is not mounted in the hand grip of such revolver, apparently due to the complicated nature of such combination lock-actuated safety mechanism.
More recent attempts to provide key-actuated safety mechanisms for revolvers are shown in U.S. Pat. No. 2,994,981 of Carrigan, issued Aug. 8, 1961, and U.S. Pat. No. 3,462,869 of Wallace, issued Aug. 26, 1969. The safety mechanisms of these patents, are mounted in the hand grip. However, in the case of the Carrigan patent, a rigid, elongated locking pin or finger is fixed to a rotating sleeve of a tumbler-type lock barrel for rotation therewith into and out of direct engagement with a shoulder on the hammer of the gun. Due to the nature of the rigid, elongated locking pin or finger, it can be bent or damaged when locked by forcing the hammer downward manually toward a cocked position. The key-actuated safety mechanism of the Wallace patent employs a lock cylinder which extends through an opening in the hammer and moves from a locked position where the hammer is engaged by a latch in the lock cylinder to an unlocked position where the latch is retracted and the lock cylinder extends outward from the side of the gun. However, this has a disadvantage in that when the gun is unlocked the lock cylinder extends from the side of the gun so that it may interfere with proper gripping of the gun. Also, since the locking mechanism is not mounted on the hand grip, it cannot be retrofitted on existing handguns.
Another key-actuated safety mechanism for a handgun is shown in U.S. Pat. No. 3,882,622 of Perloto, issued May 13, 1975, which is suitable for mounting in the side of an automatic pistol, but cannot be mounted on the hand grip of a revolver, in the manner of the present invention. In addition, this patent shows a somewhat complicated safety mechanism employing a cam which is rotated by the key actuator into engagement with a cam follower plunger in order to lock and unlock the safety mechanism.